This invention relates to a direct injection system for engines and more particularly to an improved outboard motor incorporating a direct injection system.
As is well known, in all fields of engine design there is an increasing emphasis on obtaining more effective emission control, better fuel economy and, at the same time, continued high or higher power output. This trend has resulted in the substitution of fuel injection systems for carburetors as the engine charge former. In order to obtain still further improvements, direct fuel injection systems are being considered. These systems inject fuel directly into the combustion chamber and thus have significant potential advantages.
In many applications, the incorporation of direct injection is relatively straightforward. However, in connection with outboard motors, the very compact nature of the outboard motor renders this further sophistication in engine design difficult to obtain. The problems in connection with direct fuel injection systems for outboard motors is related primarily to the space that is available and the fact that the confinement of the engine within the protective cowling can give rise to heat problems.
These problems arise, in part, because of the number of components required for fuel injection and the very nature of some of these components. For example, with manifold injection systems for outboard motors, it has been the practice to provide a fuel injection system that includes at last the following components:
a low pressure fuel pump, PA1 a high pressure fuel pump, PA1 a pressure regulator, PA1 a vapor separator; and PA1 a fuel rail for delivering the fuel to the injectors.
The use of a vapor separator is required primarily because of the confined space and the fact that fuel vapors or air in the fuel, conditions primarily resulting from heat, can cause erratic injection and poor performance.
For the same reasons, it has also been the practice to position the high pressure fuel pump in the vapor separator so as to permit it being cooled and to minimize the amount of heat that is generated in the system and to remove the heat from the fuel that is delivered to the injectors. This also saves space. However, this necessitates the use of an electrically operated fuel pump. Such pumps have has limited capacity in the pressure which they can generate.
With direct injection systems, however, the fuel must be injected directly into the combustion chamber. This means that the pressure into which the fuel is injected is higher than with manifold injection systems wherein the pressure is at substantially atmospheric or even below. Electric pumps are not totally capable of supplying such high pressures.
Therefore, in order to employ direct injection systems, it is necessary to mount the components in different locations and also to provide an arrangement wherein the high pressure pump may be driven off of the engine so as to achieve higher pressure as opposed to manifold injected engines.
It is, therefore, a principle object of this invention to provide an improved direct injection system and component layout therefore that can be utilized with outboard motors.
Another problem that somewhat complicates the positioning of components in outboard motors is the fact that the engine normally rotates with its crankshaft about a vertical axis rather than a horizontal axis in most other applications. This provides unique spatial problems, particularly when accessories are driven off of the engine crankshaft.
It is, therefore, a still further object of this invention to provide an improved fuel pump drive system and component layout for a direct injected outboard motor.
In conjunction with outboard motors as in many other applications, there is a demand for higher outputs. This results in the use of multiple cylinder engines. However, again because of the compact nature of outboard motors, if four or more cylinders are utilized, they are frequently positioned in a V arrangement. This further limits the space available for the mounting of components.
It is, therefore, a still further object of this invention to provide an improved, direct injected, V-type multi-cylinder outboard motor engine arrangement.
As is well known in this art, the air inducted into the engine may include fairly large amounts of water vapor. This may include salt water if operating in marine environments. Although the inlet devices are designed to remove the water, there is still a high water vapor content in the inducted air. This may be detrimental to precision, high pressure pumps.
It is, therefore, a still further object of this invention to provide an improved high pressure fuel pump layout for a direct injected outboard motor where the pump is protected from water vapor.
Although the pump should be protected, its drive should be cooled. It is, therefore, a still further object of this invention to provide an improved fuel pump drive system for a direct injected outboard motor where the drive is cooled by incoming air but the pump is protected from it.